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Theory of Statistics - George Mason University

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430 5 Unbiased Point Estimation<br />

Example 5.28 one-way fixed-effects AOV model<br />

Consider the linear model<br />

Yij = µ + αi + ɛij, i = 1, . . ., m; j = 1, . . ., n, (5.88)<br />

where we assume that E(ɛij) = 0 and V(ɛij) = σ2 for all i, j, and Cov(ɛij, ɛi ′ j ′) =<br />

0 if i = i ′ or j = j ′ . This can be expressed in the form <strong>of</strong> the linear<br />

model (5.66), Y = Xβ + E, where β = (µ, α1, . . ., αm) and<br />

⎡<br />

1 1 0 · · · 0<br />

⎢.<br />

⎢<br />

.<br />

⎢<br />

X = ⎢<br />

⎣<br />

. . . .<br />

. . .<br />

1 1 0 · · · 0<br />

1 0 1 · · · 0<br />

. . . . .<br />

. . .<br />

1 0 1 · · · 0<br />

. . . .<br />

.<br />

1 0 0 · · · 1<br />

. . ⎤<br />

⎥<br />

(5.89)<br />

⎥<br />

.<br />

. .<br />

. ⎦<br />

1 0 0 · · · 1<br />

and<br />

Letting<br />

Y i =<br />

Y =<br />

we may form two sums <strong>of</strong> squares<br />

and<br />

SSA = n<br />

SSE =<br />

which have the property that<br />

m<br />

n<br />

i=1 j=1<br />

m<br />

n<br />

Yij/n (5.90)<br />

j=1<br />

m<br />

Y i/m, (5.91)<br />

i=1<br />

m<br />

(Y i − Y ) 2<br />

i=1<br />

i=1 j=1<br />

(5.92)<br />

n<br />

(Yij − Y i) 2 , (5.93)<br />

(Yij − Y ) 2 = SSA + SSE. (5.94)<br />

Both SSA and SSE can be expressed as quadratic forms in matrices similar<br />

to K T n−1 Kn−1, where Kn−1 is given in equation (5.83). This is what you are<br />

asked to do in Exercise 5.7.<br />

<strong>Theory</strong> <strong>of</strong> <strong>Statistics</strong> c○2000–2013 James E. Gentle

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